1. Field of the Invention
This invention relates to a process of treating wood and/or woody products to render them suitable as a high energy food for ruminant animals and to a food product for ruminant animals.
2. Prior Art Relating to the Disclosure
The use of wood and wood products for feeding ruminant animals is not new. Ruminants include cud-chewing animals, such as cattle, sheep and goats. These animals have multicompartmented stomachs known, in order, as the rumen, reticulum, omasum and abomasum. The rumeno-reticulum is the largest part of the ruminant stomach. This organ maintains a large bacterial and protozoal population under near anaerobic conditions and functions as a fermentation vat to produce short-chain organic acids and other materials from the incoming food eaten by the animal. The short-chain organic acids are neutralized by alkaline saliva secreted by the animal. The main features of the rumen phase of digestion include: (1) fermentation of sugars, starches and cellulose to volatile fatty acids, such as acetic acid, propionic acid and butyric acid, which are absorbed and used by the animal; (2) synthesis of microbial protein from protein and non-protein in the diet of the animal; and (3) synthesis of the B-vitamins and vitamin K.
Wood and/or woody products which may be used serve two distinct functions in ruminant animals: (1) a source of roughage with little or no nutrient value, and (2) an energy source. To release the food value in wood and/or woody products requires treatment of the wood. Prerequisites for use of wood as food for ruminant animals include: (1) the economics of feeding treated wood and/or woody products compared to the cost of feeding conventional feed materials; and (2) treating of the wood (a) so that more carbohydrate nutrients are made available to the rumen micropopulation without causing excessive loss of micronutrients, (b) to effect removal of natural inhibitors in the wood that may interfere with normal rumen functions as, for examle, alkaloids and/or phenols, and (c) to not leave any residues or substances on the treated wood that are toxic to the micropopulation of the rumen or the animal in general.
It is known that the digestibility of wood and/or woody products is commensurate with the amount of lignin removed. This is particularly true with coniferous woods, such as Douglas fir, pines, hemlock and spruce. Alkaloids and other extraneous components of wood can affect the micropopulation of the rumen. A pulp food product comparatively free of extraneous components and retaining only a small portion of lignin is desired.
Pulp produced by the conventional Kraft process is not being used for feeding ruminants because of the high lignin content of the pulp. Wood pulp produced by the sulfite process, if sufficiently delignified, can be used for feeding ruminants. With either the Kraft or the sulfite process, however, it is not economical at the present time to use the pulp produced as a feed for ruminant animals compared to the cost of other available feeds on a return energy basis.
Delignification of wood using organic solvents is known. U.S. Pat. No. 2,772,968 discloses pulping of wood using triethylene glycol by heating the wood and triethylene glycol together at up to a temperature of about 125.degree. C. The chips are then washed with triethylene glycol and the triethylene glycol recovered for reuse.
U.S. Pat. No. 3,585,104 describes a pulping process using ethanol as a solvent in high pressure pulping of wood with an alkaline catalyst.
Although there has been a great deal of research work carried out on pulping with organic solvents, it has generally been oriented to making of paper pulp. Co-pending application Ser. No. 488,747, filed July 15, 1974, and entitled "Method of Providing Digestible Food for Ruminating Animals," describes a process of making a food product for ruminant animals using a triethylene glycol solvent.
Processes are known for the production of hydrolysis products from lignocellulosic material in the form of sugars for supplemental feeding of ruminants. Processes of this type are disclosed in the following U.S. Pat. Nos. 745,645; 981,634; 1,032,440; 1,190,953; 1,855,464; 2,222,885; 2,944,921; 3,212,932; 3,212,933; 3,266,933; 3,251,716 and 3,314,797.